An example of a technology related to a non-aqueous electrolyte secondary battery electrode aiming to retain a sufficient quantity of an electrolytic solution in an electrode, inhibit liquid depletion and Li ion depletion accompanying charge and discharge, and secure sufficient capacity and input/output is described in JP2006-294512A, corresponding to US2006/0234115A1, for example. The described non-aqueous electrolyte secondary battery electrode has many cracks extending in the direction intersecting with a winding direction and having a depth ranging from the surface of a mixture layer to a part in contact with a collector. The cracks are formed by curving an electrode in the longitudinal direction by turning the transfer direction with a plurality of rotatable rollers while a tension is applied to the electrode during the process of transferring the electrode in the longitudinal direction.
Further, an example of a technology related to a battery aiming at the improvement of an immersion efficiency (operability) and the inhibition of liquid leakage is described in JP07-263000A, for example. In the battery, cracks are generated on the surface and in the interior of an electrode by forcibly drying it after a composite positive electrode and a composite negative electrode are applied by coating. Examples of the cracks generated by forcible drying are hair cracks, shallow cracks, crazing, deep cracks, etc.